Alright so I'm a gr12 student studying photosynthesis right now, and I understand all the concepts as far as light dependent and independent reactions go, as well as other physiological adaptations, but what I am unclear about is the amount of photons needed to produce a PGAL molecule. So I'm asking how many nadph and ATP are produced through the 2 electrons that are excited? This is probably a simple answer but it's just unclear to me :/

I just taught that course (gr 12 photosynthesis): It appears that it is probably extremely unclear. I think it uses 4 photons per photosystem for each H2O broken. But since you need a mix of cyclic and non cyclic light reactions to produce anough ATP and NADPH, and that the cyclic reactions do not use water the total will be underestimating.

In any case I would not worry about the final sums and make sure that all the rest is understood. That is what I told my students.

Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)